Monopolies enjoy the ability to set prices, regardless of consumer needs or situations, without necessarily having to lose their customers. In a perfect competitive situation, price hikes by one company results in the loss of customers to another company. Say you have company X, Y and Z that deal in telecommunications service provision. If company X raises calling and texting rates, it would automatically lose a larger percentage of its subscribers to the other two companies. In a monopolistic environment, however, company X would retain its customers because it's the only known telecommunications service provider. Subscribers have no choice but to stay.
Monopolies enjoy the ability to make super normal profits in a short time. Take the case of a gas station established along a highway that's the only gas station within miles. In this case, the gas station is a monopoly. It has the ability to make up to 10 times as much profit as one in an area where you find a gas station every two miles. Adding a convenience store and a diner to such a station can increase profit.
Monopolies generally have the ability to control market conditions to a certain degree. Apart from controlling the product price, they can influence the perception of consumers toward a certain commodity. Because they hold a larger market share than other companies in the same field, products from monopolies are regarded as superior to others. This perceived superiority of those products lead consumers to buy them. This leads to the frustration of other companies in the same industry.
Monopolies have the advantage of numbers against their competitors. This basically means that being in the market for a longer time, their products have built a good rapport with consumers and are more trusted than products by upcoming companies. Consumers almost always prefer commodities whose performance they have experienced firsthand, unless an alternative is recommended by someone close to them. For example, women would not change a beauty cream they have used for years with desired results unless an alternative was recommended by someone else and the results are clearly seen on the person recommending the new product.